EP0188199B2 - Flugzeugfahrwerk - Google Patents

Flugzeugfahrwerk Download PDF

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Publication number
EP0188199B2
EP0188199B2 EP19860100073 EP86100073A EP0188199B2 EP 0188199 B2 EP0188199 B2 EP 0188199B2 EP 19860100073 EP19860100073 EP 19860100073 EP 86100073 A EP86100073 A EP 86100073A EP 0188199 B2 EP0188199 B2 EP 0188199B2
Authority
EP
European Patent Office
Prior art keywords
aircraft
sensor
landing gear
undercarriage
hydraulic medium
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP19860100073
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German (de)
English (en)
French (fr)
Other versions
EP0188199A2 (de
EP0188199A3 (en
EP0188199B1 (de
Inventor
Raymond Dr. Freymann
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Deutsches Zentrum fuer Luft und Raumfahrt eV
Original Assignee
Deutsches Zentrum fuer Luft und Raumfahrt eV
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Publication date
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Application filed by Deutsches Zentrum fuer Luft und Raumfahrt eV filed Critical Deutsches Zentrum fuer Luft und Raumfahrt eV
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Publication of EP0188199A3 publication Critical patent/EP0188199A3/de
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C25/00—Alighting gear
    • B64C25/32—Alighting gear characterised by elements which contact the ground or similar surface 
    • B64C25/58—Arrangements or adaptations of shock-absorbers or springs
    • B64C25/60—Oleo legs
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
    • F16F15/00—Suppression of vibrations in systems; Means or arrangements for avoiding or reducing out-of-balance forces, e.g. due to motion
    • F16F15/02—Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems
    • F16F15/023—Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems using fluid means
    • F16F15/027—Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems using fluid means comprising control arrangements

Definitions

  • the invention relates to an aircraft landing gear with a resilient and damping cylinder arrangement, according to the preamble of claim 1.
  • Such an aircraft landing gear is known from FR-A-2 386 427.
  • the additional chamber is connected to the first work space, so that the air cushion in the second work space is only influenced by the throttle by the actuation of the servo valve.
  • the invention is directed to an aircraft landing gear which is intended to enable the vibration movements of the aircraft to be reduced when taxiing on an even uneven roadway. Since fighter jets in particular also have to operate from makeshift lanes with corresponding bumps, considerable stresses occur in the takeoff and landing phases on the airframe and on the landing gear. U. can lead to structural destruction of the aircraft.
  • the previously known aircraft landing gears have a cylinder arrangement, the two working spaces filled with hydraulic medium are connected to one another via a throttle.
  • the first work space is connected to the unsprung mass of the landing gear, while the second work space is provided on the side of the airframe.
  • the work area which is arranged on the side of the airframe, also includes an air cushion, so that the spring and damping functions of the landing gear result overall.
  • These known aircraft undercarriages are designed exclusively according to the loads occurring during the landing impact, i.e. H. it is assumed that the landing shock represents the greatest load and that the forces can be absorbed anyway when rolling on a comparatively flat loading runway. The problem in connection with the dynamic structure-like behavior of the aircraft when taxiing on uneven road surfaces is therefore not given special attention.
  • the invention has for its object to develop an aircraft landing gear of the type described in such a way that the dynamic loads on the landing gear and on the airframe are reduced when taxiing even on uneven road surfaces.
  • the undercarriage must of course also be suitable for absorbing the load when landing.
  • an actively controlled aircraft undercarriage is created, which makes it possible to reduce the vibration movements and structural loads on the aircraft when taxiing on the runway by reducing the speed of the aircraft movements.
  • the air cushion contained in the undercarriage is compressed or expanded.
  • forces can be generated in the undercarriage which act as damping forces in the event of a phase shift of 90 ° relative to the undercarriage movement - i.e. in phase with the speed of the oscillating movement - and consequently reduce the oscillating movements.
  • the undercarriage must therefore work in a control loop.
  • the invention can be used on the entire landing gear of an aircraft, but can also be used on any individual landing gear unit. It is therefore also possible to use the invention in a very targeted manner for special movements: by returning the vertical speed of the center of gravity of the aircraft - via a compensation network to the servo valves of the cylinder arrangement of the main landing gear, the vertical vibration movement of the rolling aircraft can be damped.
  • the pitching movement of the rolling vehicle can be dampened by feeding the pitching speed of the aircraft back via a compensation network to the servo valve of the nose landing gear.
  • the roll movement of the aircraft that is rolling can be dampened dynamically.
  • the newly developed aircraft landing gear has similar damping properties when landing like a conventional aircraft chassis.
  • this active regulation With the introduction of this active regulation, the vibrational movements of the aircraft and thus the structural loads when taxiing can be reduced even on uneven surfaces without increasing the structural loads during the landing impact compared to a conventional landing gear. It is also advantageous that with this active regulation, in addition to the rigid body movements of the aircraft, higher-frequency vibratory movements of the elastic aircraft are reduced when taxiing on an uneven road surface.
  • the additional chamber can also be structurally combined with the one working space of the cylinder arrangement. This has the advantage that the overall height of the aircraft landing gear does not increase compared to known landing gear. The same damping effect can be achieved as with a separate arrangement of the additional chamber. Here, too, it is necessary to separate the air cushion from the additional chamber by means of a movable wall.
  • the compensation network of the control loop between the sensor and the additional chamber can, depending on the sensor design, have an integrator, in particular to integrate the accelerations recorded by a sensor designed as an accelerometer.
  • the movable wall can be suitably as a membrane made of an elastic material, for. B. rubber.
  • An additional control loop with pressure transmitter and PID controller can be provided to determine the stationary working point, which sets the pressure in the additional chamber. Static control of the chassis is thus possible.
  • the pressure in the additional chamber is used as a static control variable.
  • sensors - in particular acceleration sensors - can also be arranged distributed on the aircraft, the signals of which, after being superimposed, are fed to the individual units of the landing gear.
  • the signals of which, after being superimposed, are fed to the individual units of the landing gear.
  • the electrical signals from the sensors are correspondingly superimposed and fed via an electronic compensation network to the electrohydraulic servo valves of the individual units of the chassis as a manipulated variable.
  • a conventional chassis is shown schematically with the essential parts in the present context.
  • the landing gear 2 On the runway 1, the landing gear 2 is shown with the aircraft cell 3, which is symbolically represented as the aircraft mass.
  • a cylinder arrangement with two working spaces 4 and 5 is provided in the manner shown, which are connected to one another via a throttle 6. Both work rooms 4 and 5 are filled with hydraulic medium.
  • An air cushion 7 is located above and enclosed in the work space 5.
  • the known undercarriages are constructed according to this principle.
  • FIG. 2 shows a first embodiment of the invention, similarly schematized as FIG. 1.
  • an additional chamber 8 is provided, which is operatively connected to the air cushion 7 of the working space 5 via a movable wall 9.
  • the additional chamber 8 is connected via a servo valve 10 to a pressure source for hydraulic medium, not shown.
  • a supply line 11 and a discharge line 12 are provided, both of which lead to the pressure source.
  • Fig. 3 illustrates an alternative embodiment form, in which the additional chamber 8 and the work space 5 are structurally combined. This design has the advantage of a lower chassis height.
  • a sensor 13 is attached as an acceleration sensor, which emits the electrical signal X , which reaches a integrator via a line 14, which is connected to a compensation network 17 via a line 16.
  • Line 16 carries the signal x.
  • a line 18 connects the compensation network 17 to the electrohydraulic servo valve 10.
  • FIGS. 4 to 6 the functional principle and the structure of the control system are exemplified for the case of a one-mass oscillator.
  • the sensor 13 designed as an acceleration sensor, the acceleration of the mass that loads the chassis is determined.
  • the integrated acceleration signal which is in phase with the speed of movement of the mass, is fed to an electronic compensation network 17. There it is amplified and filtered if necessary.
  • the electro-hydraulic servo valve 10 is controlled with the electrical output signal of the compensation network. This valve regulates the inflow and outflow of the hydraulic medium into the additional chamber 8 of the chassis. This flow of the hydraulic medium in turn causes the air cushion 7 enclosed in the chassis to be compressed or expanded, as a result of which the damping forces are generated.
  • Fig. 7 clearly shows the function of three controls, namely the return of the vertical speed, the return of the rolling speed and the return of the pitching speed.
  • the airframe 3 has an inertial platform 19 which is connected to an on-board computer 20. From this lead a line 21 for the vertical speed of the center of gravity, a line 22 for the rolling speed and a line 23 for the pitching speed to the compensation network 17 and from there in the manner shown to the individual units of the overall chassis.
  • Fig. 8 illustrates the additional control loop for the static control of the vehicle.
  • a pressure transmitter 24 is provided on the additional chamber 8, from which a line 25 leads to a PID controller 26, from which a line 27 leads to a subtraction element 28, which is switched on in line 18, which connects the compensation network 17 with the connects electro-hydraulic servo valve.
  • the pressure P in the additional chamber can be used as a static control variable to determine the stationary working point, that is to say to achieve the static control of the undercarriage.
  • 9 to 16 each show associated and assigned diagrams of the amplitude of the various movements over frequency.
  • FIGS. 9 and 10 show calculation results in the event that only the control loop acting on the main running gear for damping the vertical movement (FIG. 7) is closed (i.e. active).
  • the solid line shows the unregulated behavior, the dashed line the regulated behavior.
  • the Nyquist locus for the open control loop shown in FIG. 11 indicates the good stability of the closed control loop; the point (-1.0, i 0) is not enclosed.
  • FIG. 12 and 13 show calculation results in the event that only the control loop acting on the nose gear for damping the pitching movement is closed (FIG. 7).
  • the locus for the open control loop shown in FIG. 14 illustrates the good stability of the closed control loop.

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  • Engineering & Computer Science (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Vibration Prevention Devices (AREA)
EP19860100073 1985-01-12 1986-01-04 Flugzeugfahrwerk Expired - Lifetime EP0188199B2 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3500929 1985-01-12
DE19853500929 DE3500929A1 (de) 1985-01-12 1985-01-12 Flugzeugfahrwerk

Publications (4)

Publication Number Publication Date
EP0188199A2 EP0188199A2 (de) 1986-07-23
EP0188199A3 EP0188199A3 (en) 1987-05-13
EP0188199B1 EP0188199B1 (de) 1990-01-17
EP0188199B2 true EP0188199B2 (de) 1992-10-14

Family

ID=6259746

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19860100073 Expired - Lifetime EP0188199B2 (de) 1985-01-12 1986-01-04 Flugzeugfahrwerk

Country Status (2)

Country Link
EP (1) EP0188199B2 (enrdf_load_stackoverflow)
DE (1) DE3500929A1 (enrdf_load_stackoverflow)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8807891D0 (en) * 1988-04-05 1988-05-05 Dowty Rotol Ltd Suspension arrangement
DE3935376A1 (de) * 1989-10-24 1991-04-25 Bosch Gmbh Robert Verfahren und vorrichtung zur fahrwerkregelung
FR2667907B1 (fr) * 1990-10-15 1993-02-05 Renault Dispositif d'asservissement en effort d'un verin hydraulique et suspension de vehicule automobile munie d'un tel dispositif.
CN103466085B (zh) * 2013-07-24 2015-12-23 宁波大学 一种保持高空坠物平衡的自适应液压多触角调节器
CN105480431B (zh) * 2014-10-11 2017-10-31 中国航空工业集团公司西安飞机设计研究所 一种避免起落架离地状态过度振动的方法

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1474774A (fr) * 1964-12-02 1967-03-31 Amortisseur hydraulique des oscillations comportant un réglage automatique du niveau et destiné plus particulièrement aux véhicules à moteur
DE2715895C2 (de) * 1977-04-09 1979-05-31 Messerschmitt-Boelkow-Blohm Gmbh, 8000 Muenchen Federbein, vorzugsweise für Flugzeugfahrwerke
DE2943486C2 (de) * 1979-10-27 1986-07-17 Messerschmitt-Boelkow-Blohm Gmbh, 8012 Ottobrunn Einrichtung zur Stoß- und Schwingungsdämpfung für Fahrzeuge

Also Published As

Publication number Publication date
EP0188199A2 (de) 1986-07-23
EP0188199A3 (en) 1987-05-13
DE3500929C2 (enrdf_load_stackoverflow) 1992-07-02
DE3500929A1 (de) 1986-07-17
EP0188199B1 (de) 1990-01-17

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